It is known to use four electrodes to measure the internal impedance of the body to determine a quantity related to internal body fat. This known scheme for measuring internal impedance is pictured in FIG. 24. The equipment includes a measuring device 1 connected to electrodes 2 and 3 by lead wires 6, and which apply a high-frequency signal; and electrodes 4 and 5, which measure the resistance of the body. The patient is made to lie on a bed, electrodes 2 and 3 are attached to the patient's right hand and right foot, and electrodes 4 and 5, which measure the resistance of the body, are attached to the right hand and foot close to electrodes 2 and 3, respectively. A high-frequency signal is applied to electrodes 2 and 3 by device 1, causing a current to pass into the patient's body. The potential difference between electrodes 4 and 5 is measured, and the impedance of the patient's body can be obtained from this potential difference and the strength of the current which was passed.
The inventor has found that devices such as shown in FIG. 24 suffer from the following problems.
(1) To prevent errors resulting from variation in the path of the current, and to ensure that the measurement would be sufficiently accurate, the patient had to be lying down. The patient's feet had to be spread so that there was no danger that they would touch each other, and the hands had to be kept well away from the torso. (2) Because of the aforesaid restrictions on the patient, and because of the difficulty of attaching the electrodes and conducting the test, a special technician was needed. The patient could not perform the test without medical supervision, and hence the device was not suitable for use in the home. (3) Since this device is designed to be used for the treatment of a great number of patients, it has a large key input and display unit, a printer, an AC power supply, and other components. This makes the device large and unwieldy. (4) The use of numerous electrodes with their extension cables made preparation and cleanup difficult. (5) Just as with an ECG, a user had to apply a conductor such as keratin cream to the portion of the hands and feet where the electrodes were to be attached so as to minimize the effect of contact resistance. (6) In estimating body fat by measuring impedance, impedance data for the body are more important than those for the hands and feet. Between the points where it is measured in the existing scheme, however, the impedance of the hand and foot is considerably larger than that of the body. The impedance of joints is especially high. It is well known that disparities between small- and large-boned people and those with small joints exert a profound effect on measurement results.
For example, here are some results of measuring the impedance at different parts of the body.
1) Male with thick limbs: Between right hand and right foot, 350.OMEGA.; right arm, 150.OMEGA.; right foot, 130.OMEGA.; thoracic region, 70.OMEGA.
2) Female with slender limbs: Between right hand and right foot, 675.OMEGA.; right arm, 360.OMEGA.; right foot, 240.OMEGA.; thoracic region, 75.OMEGA.
3) Wrist joint: 25 to 50.OMEGA. level
Furthermore, there are in general two types of obesity, subcutaneous and visceral. Though two patients may be similarly overweight, the viscerally obese patient will be prone to suffer from irregularities of sugar metabolism, such as high blood sugar or high blood insulin, and of fat metabolism, such as high blood cholesterol. The percentage of visceral fat in total internal fat is a significant criterion which can indicate whether the obesity is of the subcutaneous or visceral variety. At present, the only way to perform this test is with a large, highly accurate and extremely expensive device such as an X ray CT or MRI scanner. There has been a demand for a device employing a much simpler measurement scheme.
This invention was developed in view of the inventors noting the problems discussed above. The objective of the present invention is to provide a device which can supply data that would be useful as a guide for home health management. The present invention allows the patient to easily be able to measure the impedance developed across the body. The device determines the amount and ratio of visceral fat and the type of obesity. It would be compact, light, and inexpensive, and the accuracy of its measurements would be high. An individual is able to use the device in the privacy of their own home.
The device to provide data as a guide to health management includes: 1) a portable main unit with grip area for the right and left hands, furnished on either end of the main unit, each of which has an electrode to apply a high-frequency signal and an electrode to measure the resistance of the body. A foot electrode unit is connected by a cable to the aforesaid main unit, and has electrodes to apply high-frequency signals and electrodes to measure the electrical potential developed across the body. The portable main unit mentioned above has a first high frequency generator that generates a high-frequency signal which passes through both the shallow part of the body (where subcutaneous fat is located) and the deeper part of body (where visceral fat is located). A second frequency generator generates high-frequency signal which passes mainly in the deeper part of the body. An electrode selecting device selects which two of the aforesaid pairs of electrodes will be used by a switching operation.
A frequency selecting device switches frequencies to select one of the aforesaid series of high-frequency signals, and it applies them between the first electrodes of the selected pairs. The impedance between the two pairs of electrodes from the electrical potential detected across the respective second electrode in each of the pairs is detected, and this is used to calculate the visceral fat mass based on the impedances measured when the two high-frequency signals are applied. Other specific physical data which have been entered independently, such as weight, can also be used.
The patient uses this device by grasping the grips with both hands so that each hand makes contact with the two electrodes in the grip. The user steps onto the stand, causing the sole of each foot to make contact with the two foot electrodes. By operating the device to switch electrodes and the device to switch frequencies, the user can easily measure the impedance between the various locations while in a standing position.
The portion of the impedance attributable to the limbs can be calculated by adding the value of the impedance between the feet (Z.sub.2f) to the value of the impedance between the hands (Z.sub.2h). These values are subtracted from the value of the impedance between hand and foot (Z.sub.2b) to obtain the impedance value for the thoracic region alone (Z.sub.2s). From this impedance data and specific physical data input by the patient, the visceral fat mass can be calculated: EQU Z.sub.2s =Z.sub.2b -(Z.sub.2h +Z.sub.f2)/2
Another aspect of this application calculates, from the values for total body fat mass and visceral fat mass obtained by the device discussed above, a value for subcutaneous fat mass, and calculates the ratio of visceral to subcutaneous fat masses. From this ratio, the present invention allows a determination of whether the obesity is of the subcutaneous or visceral type.
Another aspect of this application provides elements including: 1) a portable main unit; 2) grips for the right and left hands, furnished on either end of the main unit, each of which has an first electrode to apply a high-frequency signal and an second electrode to measure the resistance of the body; 3) a foot electrode unit, connected by a cable to the aforesaid main unit, which has electrodes to apply high-frequency signals and electrodes to measure the electrical potential developed across the body.
The portable main unit mentioned above is equipped with the following: 1) a high frequency generator has a high-frequency signal which passes through both the shallow part of the body (where subcutaneous fat is located) and the deeper part of the body (where visceral fat is located), 2) an electrode selecting device including switches connected to establish connections that select any two of the aforesaid first and second electrodes; 3) an impedance measuring device to measure the impedance between the two pairs of electrodes from the electrical potential detected across the respective second electrode in each of the pairs; 4) a estimating device which estimates a waist-to-hip ratio based on the data concerning impedance between the two pairs of electrodes measured by the device for that purpose, and on specific physical data which have been entered independently; and 5) a calculating device to calculate visceral fat mass based on the waist-to-hip ratio which has been estimated.
This device can, for example, measure the impedance Z.sub.f between the patient's feet, the impedance Z.sub.h between the patient's hands, and/or the impedance Z.sub.b between hand and foot. From these values the impedance Z.sub.s of the thoracic region is obtained.
The device uses the impedance Z.sub.fs of the hip region, which is obtained from the hand-to-hand impedance Z.sub.h and the foot-to-foot impedance Z.sub.f, and the impedance Z.sub.s of the thoracic region, to estimate a waist-to-hip ratio. It estimates the visceral fat mass and the visceral-to-subcutaneous fat ratio using this waist-to-hip ratio, the total body fat ratio, the converted fat and other values.
The present invention allows accurate measurement of body fat ratio and visceral fat mass. The measurement is not affected by differences in the density of patients' hands and feet. It provides, in a simple and reliable fashion, a measurement of visceral fat mass, which is a crucial datum in health management.
This device allows obtaining a value for the subcutaneous fat mass as well as the visceral-to-subcutaneous fat ratio. This allows an evaluation to be made as to whether the patient's obesity is of the subcutaneous or visceral variety.
This device uses the various measured impedance values to estimate a waist/hip ratio, and from this estimated waist/hip ratio it calculates an estimate of body fat mass. From this it is able to obtain a value for visceral fat mass, a crucial datum in health management. Using the patient's waist/hip ratio to supplement the physical data, the device can provide, in a simple and reliable fashion, such critical values as the proportional index, the amount and ratio of visceral fat within the total fat mass, and whether the obesity is of the subcutaneous or visceral variety.